Venous stent with high flexibility

Abstract

The invention relates to a vein stent with high flexibility, a far-end woven stent is formed by weaving metal wires with coatings and has high flexibility, and the expansion diameter of the stent is slightly larger than the diameter of a target vein but smaller than that of a near-end laser engraving stent; the far-end woven stent comprises a metal wire and a coating located outside the metal wire, the coating is divided into an inner side coating and an outer side coating, the radian proportion of the inner side coating is larger than that of the outer side coating, and the surface roughness of the inner side coating is smaller than that of the outer side coating; and the group of metal connecting short rods are connected with the near-end laser engraving bracket and the woven bracket through welding. The stent has different structure and mechanical characteristics in vein segments with different anatomy and kinematic mechanics characteristics, is better in targeted adaptability, and can better meet the requirements of stent fixation and cross-joint stent placement in iliofemoral vein stent implantation of patients with non-thrombotic iliofemoral vein stenosis occlusion diseases.

Description

Technical Field

[0001] The invention relates to a venous stent, in particular to a venous stent with high flexibility, belonging to the technical field of vascular stents. Background Art

[0002] Non-thrombotic iliofemoral venous stenosis and occlusive disease is one of the most common and important diseases in vascular surgery. It has a high prevalence, brings huge medical and labor burdens, and significantly affects patients' limb function and quality of life. With the progress of endovascular treatment methods, iliofemoral percutaneous stent angioplasty has gradually replaced traditional open bypass surgery and become an important means of clinical treatment of deep vein disease. It has the advantages of less trauma, quick recovery, short operation time, and a patency rate much higher than that of open bypass surgery.

[0003] However, the venous stents currently used in clinical practice still have many shortcomings. The medical market currently uses laser-engraved stents and braided stents. For laser-engraved stents, the entire stent has a consistent pressure resistance, which often results in the stent collapsing in the compressed area, while the stent lacks flexibility in the uncompressed area; in addition, the stent is prone to angles at the bends of the iliac vein, which may increase damage to the endothelium, cause intra-stent venous intimal hyperplasia and recurrence of thrombosis. For braided stents, the stent has better flexibility and less damage to the tube wall, but the radial support force is insufficient, and complications such as stent displacement may occur. Summary of the invention

[0004] The purpose of the present invention is to provide an asymmetric venous stent with increased friction in the anchoring area, which can ensure that the stent has the characteristics of not affecting the contralateral venous blood flow at the confluence of the two iliac veins, strengthening the radial support force of the proximal iliac vein, strong flexibility in the cross-joint segment, high flexibility in the distal anchoring area and strong friction.

[0005] The present invention adopts the following technical solutions:

[0006] A highly flexible venous stent comprises a three-part stent and a group of metal connecting short rods 5; the three parts of the stent are respectively: a proximal stent 1, a strong radial support force stent 2, and a distal braided stent 4 connected in sequence from the proximal end to the distal end; the proximal stent 1 is positioned at the junction of the two iliac veins, the strong radial support force stent 2 is positioned at the easily compressed segment of the common iliac vein, and the distal braided stent 4 is positioned at the distal end of the common iliac vein and the external iliac vein; the radial support force of the three parts of the stent decreases in this order: the proximal stent 1> the strong radial support force stent 2> the distal braided stent 4; the flexibility of the three parts of the stent decreases in this order: The distal braided stent 4 is higher than the strong radial support stent 2 and higher than the proximal stent 1; the distal braided stent 4 is formed by weaving coated metal wires, and the expanded diameter of the stent is slightly larger than the target vein diameter but smaller than the strong radial support stent 2; the distal braided stent 4 includes a metal wire 401, and a coating located outside the metal wire 401, and the coating is divided into an inner coating 402 and an outer coating 403, and the curvature of the inner coating accounts for a larger proportion than the outer coating 403, and the surface roughness of the inner coating 402 is smaller than that of the outer coating 403; the group of metal connecting short rods 5 are connected to the laser engraved stent 2 and the braided stent 4 by laser welding.

[0007] Preferably, the most proximal end of the proximal stent 1 is in the shape of a petal that opens slightly toward the periphery.

[0008] Preferably, the proximal stent 1 is an open-design bare metal stent manufactured by laser engraving technology; the material includes but is not limited to one of stainless steel, cobalt-chromium alloy, platinum-chromium alloy, and magnesium alloy.

[0009] Furthermore, the strong radial support stent 2 is a bare metal stent manufactured by laser engraving technology, the expanded diameter of the stent is larger than the target vein diameter, the metal wall thickness and metal coverage are larger than the proximal stent 1, and the length is 2-4 cm.

[0010] Furthermore, the density of the metal wire 401 is lower than that of the strong radial supporting force stent 2 , and the stent expansion diameter is smaller than the stent expansion diameter of the strong radial supporting force stent 2 .

[0011] Furthermore, the coating is a polymer coating, the coating material is polylactic acid-glycolic acid copolymer PLGA, the surface roughness of the outer coating 403 that contacts the blood vessel wall is about 0.8-1.2 μm, and the surface roughness of the inner coating 402 is less than 50 nm.

[0012] Furthermore, the distal braided stent 4 has a length of 4-6 cm and covers the iliac vein across the joint.

[0013] Preferably, the curvature range of the inner coating 402 is in the range of 240°-270°, and the remaining part is the curvature range of the outer coating 403 .

[0014] Furthermore, the thickness of the inner coating layer 402 and the outer coating layer 403 are equal.

[0015] The beneficial effects of the present invention are:

[0016] 1) The stent has different structural and mechanical characteristics in vein segments with different anatomical and kinematic characteristics, and has better targeted adaptability, which can better meet the needs of stent fixation and cross-joint stent placement during iliofemoral vein stent implantation in patients with non-thrombotic iliofemoral vein stenosis and occlusive disease.

[0017] 2) It can ensure that the stent has the characteristics of not affecting the contralateral venous blood flow at the confluence of the two iliac veins (the metal density of the proximal stent is low and the design is petal-like), the radial support force of the proximal iliac vein is enhanced (the design of the strong radial support force stent), and the distal anchoring area is highly flexible and has strong friction (the design of the two-part coating of the distal braided stent). BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic structural diagram of the venous stent with high flexibility of the present invention.

[0019] Figure 2 yes Figure 1 Schematic diagram of an enlarged cross section of the metal wire of the distal braided stent.

[0020] Figure 3 It is a schematic diagram of the highly flexible venous stent of the present invention after being implanted into a human blood vessel.

[0021] Figure 4 It is a schematic diagram of the strong radial support stent and the distal braided stent connected by a short rod.

[0022] In the figure, 1. proximal stent, 2. strong radial support stent, 4. distal braided stent, 401. metal wire, 402. inner coating, 403. outer coating, 5. short rod. DETAILED DESCRIPTION

[0023] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0024] The present invention continues that the ideal venous stent should have the following features:

[0025] 1. The confluence of the bilateral iliac veins needs to ensure smooth blood flow, and stent implantation does not affect the contralateral venous blood flow;

[0026] 2. The stent in the proximal iliac vein anchoring area requires strong radial support force;

[0027] 3. The stent for the vein crossing the joint segment needs to be highly flexible;

[0028] 4. The stent at the distal anchoring area of ​​the external iliac vein needs to maintain high flexibility and increase friction to ensure the stability of the distal anchoring area.

[0029] Therefore, designing and manufacturing an asymmetric stent that does not affect the contralateral venous blood flow at the confluence of the bilateral iliac veins, has strong radial support at the proximal iliac vein, strong flexibility across the joint segment, high flexibility in the distal anchoring area, and strong friction is of great significance for venous reconstruction in patients with non-thrombotic iliofemoral venous stenosis and occlusive disease.

[0030] In view of the shortcomings of the current venous stents, this embodiment specifically provides an asymmetric stent, the structure of which includes: an open design stent at the confluence of the two iliac veins, a laser engraved stent with strong radial support in the proximal anchoring area of ​​the iliac veins, a highly flexible braided stent across the joint segment, and a high-friction coating on the metal braided wire. This design can ensure that the stent has the characteristics of not affecting the contralateral venous blood flow at the confluence of the two iliac veins, strong radial support at the proximal iliac veins, high flexibility across the joint segment and the distal anchoring area, and strong friction.

[0031] See also Figure 1-2 A highly flexible venous stent comprises a three-part stent and a group of metal connecting short rods 5; the three parts of the stent are respectively: a proximal stent 1, a strong radial support stent 2, and a distal braided stent 4 connected in sequence from the proximal end to the distal end; the proximal stent 1 is positioned at the junction of the two iliac veins, the strong radial support stent 2 is positioned at the easily compressed segment of the common iliac vein, and the distal braided stent 4 is positioned at the distal end of the common iliac vein and the external iliac vein; the radial support force of the three parts of the stent decreases in this order: the proximal stent 1> the strong radial support stent 2> the distal braided stent 4; the flexibility of the three parts of the stent decreases in this order: The distal braided stent 4> the strong radial support stent 2> the proximal stent 1; the distal braided stent 4 is formed by braiding coated metal wires, and the stent expansion diameter is slightly larger than the target vein diameter but smaller than the strong radial support stent 2; the distal braided stent 4 includes metal wires 401 and a coating located outside the metal wires 401, the coating is divided into an inner coating 402 and an outer coating 403, the curvature of the inner coating accounts for a larger proportion than the outer coating 403, and the surface roughness of the inner coating 402 is smaller than that of the outer coating 403; the group of metal connecting short rods 5 connects the laser engraved stent 2 and the braided stent 4 by laser welding. See Figure 1-2 :

[0032] Bi-iliac confluence open design stent 1: including but not limited to open design bare metal stent manufactured by laser engraving technology, materials include but are limited to stainless steel, cobalt-chromium alloy, platinum-chromium alloy, magnesium alloy. The stent has large pores and low metal wire density, and the interference with blood flow is reduced by increasing the pores of the stent and reducing the metal density. The proximal opening of the stent is slightly larger and petal-shaped, ensuring that when both iliac veins are implanted with the stent of this design, the stents at the confluence of the two iliac veins are staggered, which is not easy to affect the blood flow on both sides. (The materials of other bare metal stent parts are the same as above)

[0033] Stent proximal anchoring area strong radial support stent 2: including but not limited to metal bare stents manufactured by laser engraving technology, with large stent expansion diameter (larger than the target vein diameter), thick metal wall, dense metal distribution, and increased radial support of the stent proximal anchoring area by means of large stent expansion diameter, thick metal wall, and high metal coverage. Length 2-4cm, covering the iliac vein segment that is easily compressed by arteries and spine.

[0034] Braided stent 4 at the distal end of the stent: It is woven from coated metal wires. The density of the metal wires is low, the expanded diameter of the stent is small (slightly larger than the target vein diameter), and it has high flexibility. A polymer coating is added to the outside of the bare stent. The coating materials include but are not limited to polylactic acid-glycolic acid copolymer (PLGA). The surface roughness of the coating in contact with the blood is small (less than 50nm) and high in smoothness, which prevents platelets and blood cells from adhering to the inside of the stent and causing thrombosis in the stent; the surface roughness of the coating in contact with the blood vessel wall is large (about 1μm) and relatively rough, which is conducive to cell adhesion. By increasing friction and promoting close bonding between the implant and the blood vessel wall, the friction of the distal anchoring area of ​​the stent is increased, which is conducive to stent fixation. The length is 4-6cm, covering the iliac vein trans-articular stage. Metal connecting short rod 5: The laser engraved stent 2 and the braided stent 4 are connected by laser welding. The shape of the short rod 5 can be curved, such as Figure 4 As shown, it can also be a straight line (not shown in the drawings). Figure 2 :

[0035] The metal wire 401 of the braided stent 4 in the distal anchoring region of the stent is made of materials including but not limited to stainless steel, cobalt-chromium alloy, platinum-chromium alloy, magnesium alloy, and the like.

[0036] The inner coating 402 of the braided stent 4 in the distal anchoring area of ​​the stent, the coating material includes but is not limited to polylactic acid-glycolic acid copolymer (PLGA), etc., the surface roughness of the coating contacting the blood is small (less than 50nm) and the smoothness is high, so as to avoid the adhesion of platelets and blood cells inside the stent and cause the formation of thrombosis in the stent

[0037] The outer side coating 403 of the braided stent 4 in the distal anchoring area of ​​the stent, the coating material includes but is not limited to polylactic acid-glycolic acid copolymer (PLGA), etc. The surface roughness of the part of the coating in contact with the blood vessel wall is large (about 1μm) and relatively rough, which is conducive to cell adhesion. By increasing the friction force and promoting the close combination of the implant and the blood vessel wall, the friction force of the distal anchoring area of ​​the stent is increased, which is conducive to the fixation of the stent.

[0038] When the stent is implanted, see Figure 3 :

[0039] The biiliac confluence was openly designed with stent 1, and the stent was implanted into the inferior vena cava.

[0040] The strong radial support stent 2 in the proximal anchoring area of ​​the stent is anchored at the proximal end of the iliac vein, has a length of 2-4 cm, and covers the venous segment of the iliac vein that is easily compressed by the artery and spine.

[0041] The braided stent 4 in the distal anchoring area of ​​the stent has high flexibility, a length of 4-6 cm, covers the main lesion area including the iliac vein cross-articular segment, is anchored in the external iliac vein, and has high flexibility and strong friction.

[0042] The stent has different structural and mechanical characteristics in vein segments with different anatomical and kinematic characteristics, and can meet the needs of stent fixation and cross-joint stent placement during iliofemoral vein stent implantation in patients with non-thrombotic iliofemoral vein stenosis and occlusive disease.

[0043] The above are preferred embodiments of the present invention. A person skilled in the art may make various changes or improvements on this basis. Without departing from the general concept of the present invention, these changes or improvements should fall within the scope of protection claimed by the present invention.

Claims

1. A highly flexible venous stent, characterized in that: It includes a three-part bracket and a set of metal connecting short rods (5); The three parts of the stent are, from the proximal end to the distal end, respectively: a proximal stent (1), a strong radial support stent (2), and a distal braided stent (4) which are connected in sequence; The proximal stent (1) is positioned at the junction of the two iliac veins, the strong radial support stent (2) is positioned at the easily compressed segment of the common iliac vein, and the distal braided stent (4) is positioned at the distal end of the common iliac vein and the external iliac vein; The radial support force of the three-part stent decreases in this order: proximal stent (1) > strong radial support force stent (2) > distal braided stent (4); The flexibility of the three-part stent decreases in this order: distal braided stent (4) > strong radial support stent (2) > proximal stent (1); The distal braided stent (4) is formed by braiding coated metal wires, and the expanded diameter of the stent is slightly larger than the diameter of the target vein but smaller than the strong radial support stent (2); the distal braided stent (4) comprises metal wires (401) and a coating located outside the metal wires (401), the coating is divided into an inner coating (402) and an outer coating (403), the curvature of the inner coating accounts for a larger proportion than that of the outer coating (403), and the surface roughness of the inner coating (402) is smaller than that of the outer coating (403); The group of metal connecting short rods (5) connects the laser engraved bracket (2) and the braided bracket (4) by welding.

2. The highly flexible venous stent according to claim 1, characterized in that: The most proximal end of the proximal support (1) is in the shape of a petal that opens slightly toward the periphery.

3. The highly flexible venous stent according to claim 1, characterized in that: The proximal stent (1) is an open-design bare metal stent manufactured by laser engraving technology; the material includes one of stainless steel, cobalt-chromium alloy, platinum-chromium alloy, and magnesium alloy.

4. The highly flexible venous stent according to claim 3, characterized in that: The strong radial support stent (2) is a bare metal stent manufactured by laser engraving technology. The expanded diameter of the stent is larger than the diameter of the target vein, the metal wall thickness and metal coverage are larger than the distal braided stent (1), and the length is 2-4 cm.

5. The highly flexible venous stent according to claim 4, characterized in that: The density of the metal wires (401) is lower than that of the strong radial support force stent (2), and the stent expansion diameter is smaller than the stent expansion diameter of the strong radial support force stent (2).

6. The highly flexible venous stent according to claim 5, characterized in that: The coating is a polymer coating, the coating material is a blood-compatible coating, the surface roughness of the outer coating (403) in contact with the blood vessel wall is about 0.8-1.2μm, and the surface roughness of the inner coating (402) in contact with blood is less than 50nm.

7. The highly flexible venous stent according to claim 6, characterized in that: The blood-compatible coating is polylactic-co-glycolic acid (PLGA).

8. The highly flexible venous stent according to claim 5, characterized in that: The distal braided stent (4) is 4-6 cm in length and covers the transarticular stage of the iliac vein.

9. The highly flexible venous stent according to claim 1, characterized in that: The curvature range of the inner coating (402) is in the range of 240°-270°, and the remaining part is the curvature range of the outer coating (403).

10. The highly flexible venous stent according to claim 9, characterized in that: The thickness of the inner coating layer (402) and the outer coating layer (403) are equal.

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